IN the foregoing eight chapters we have contemplated, under their several heads, those "Difficulties of the Social Science" which the chapter bearing that title indicated in a general way. After thus warning the student against the errors he is liable to fall into, partly because of the nature of the phenomena themselves and the conditions they are presented under, and partly because of his own nature as observer of them—which by both its original and its acquired characters causes twists of perception and judgment—it now remains to say something about the needful preliminary studies. I do not refer to studies furnishing the requisite data, but I refer to studies giving the requisite discipline. Right thinking in any matter depends very much on the habit of thought; and the habit of thought, partly natural, depends in part on the artificial influences to which the mind has been subjected.

As certainly as each person has peculiarities of bodily action that distinguish him from his fellows, so certainly has he peculiarities of mental action that give a character to his conceptions. There are tricks of thought as well as tricks of muscular movement. There are acquired mental aptitudes for seeing things under particular aspects, as there are acquired bodily aptitudes for going through evolutions after particular ways. And there are intellectual perversities produced by certain modes of treating the mind, as there are incurable awkwardnesses due to certain physical activities daily repeated.

A truth ever to be remembered is, that each kind of mental discipline, besides its direct effects on the faculties brought into play, has its indirect effects on the faculties left out of play; and when special benefit is gained by extreme special discipline, there is inevitably more or less general mischief entailed on the rest of the mind by the consequent want of discipline. That antagonism between body and brain which we see in those who, pushing brain-activity to an extreme, enfeeble their bodies, and those who, pushing bodily activity to an extreme, make their brains inert, is an antagonism which holds between the parts of the body itself and the parts of the brain itself. The greater bulk and strength of the right arm resulting from its greater use, and the greater aptitude of the right hand, are instances in point; and that the relative incapacity of the left hand, involved by cultivating the capacity of the right hand, would become still more marked were the right hand to undertake all manipulation, is obvious. The like holds among; the mental faculties. The fundamental antagonism between feeling and cognition, running down through all actions of the mind, from the conflicts between emotion and reason to the conflicts between sensation and perception, is the largest illustration. We meet with a kindred antagonism, among the actions of the intellect itself, between perceiving and reasoning. Men who have marked aptitudes for accumulating observations are rarely men given to generalizing; while men given to generalizing are commonly men who, mostly using the observations of others, observe for themselves less from love of particular facts than from desire to put such facts to use. We may even trace the antagonism within a narrower range, between general reasoning and special reasoning. One prone to far-reaching speculations rarely pursues to much purpose those investigations by which particular truths are reached; while the scientific specialist ordinarily has but little tendency to occupy himself with wide views.

No more is needed to make it clear that habits of thought result from particular kinds of mental activity, and that each man's habits of thought influence his judgment on any question brought before him. It will be obvious, too, that, in proportion as the question is involved and many-sided, the habit of thought must be a more important factor in determining the conclusion arrived at. Where the subject-matter is very simple, as a geometrical truth or a mechanical action, and has therefore not many different aspects, perversions of view consequent on intellectual attitude are comparatively few; but, where the subject-matter is complex and heterogeneous, and admits of being mentally seen in countless different ways, the intellectual attitude affects very greatly the form of the conception.

A fit habit of thought, then, is all-important in the study of Sociology; and a fit habit of thought can be acquired only by study of the Sciences at large. For Sociology is a science in which the phenomena of all other sciences are included. It presents those necessities of relation with which the Abstract Sciences deal; it presents those connections of cause and effect which the Abstract-Concrete Sciences familiarize the student with; and it presents that concurrence of many causes and production of contingent results which the Concrete Sciences show us, but which we are shown especially by the organic sciences. Hence, to acquire the habit of thought conducive to right thinking in Sociology, the mind must be familiarized with the fundamental ideas which each class of sciences brings into view, and must not be possessed by those of any one class, or any two classes, of sciences. That this may be better seen, let me briefly indicate the indispensable discipline which each class of sciences gives to the intellect, and also the wrong intellectual habits produced if that class of sciences is studied exclusively.

Entire absence of training in the Abstract Sciences leaves the mind without due sense of necessity of relation. Watch the mental movements of the wholly ignorant, before whom not even the exact and certain results of Arithmetic have been frequently brought, and it will be seen that there exists nothing like irresistible conviction that from given data there is an inevitable inference. That which to you has the aspect of a necessity, seems to them not free from doubt. Even men whose educations have made numerical processes and results tolerably familiar, will show, in a case where the implication is logical only, that they have not absolute confidence in the dependence of conclusion on premisses.

Unshakable beliefs in necessities of relation, are to be gained only by studying the Abstract Sciences, Logic and Mathematics. Dealing with necessities of relation of the simplest class, Logic is of some service to this end; though often of less service than it might be, for the reason that the symbols it uses are not translated into thought, and the connections stated not really represented. Only when, for a logical implication expressed in the abstract, there is substituted an example so far concrete that the interdependencies can be contemplated, is there an exercise of the mental power by which logical necessity is grasped. Of the discipline given by Mathematics, also, it is to be remarked that the habit of dealing with the necessities of numerical relation, though in a degree useful for cultivating the consciousness of necessity, is not in a high degree useful; because, in the immense majority of cases, the mind, occupied with the symbols used, and not passing beyond them to the groups of units they stand for, does not really figure to itself the relations expressed—does not really discern their necessities, and has not therefore the conception of necessity perpetually repeated. It is the more special division of Mathematics, dealing with Space-relations, which, above all other studies, yields necessary ideas, and so makes strong and definite the consciousness of necessity in general. A geometrical demonstration time after time presents premisses and conclusion in such wise that the relation alleged is seen in thought—cannot be passed over by mere symbolization. Each step exhibits some connection of positions or quantities as one that could not be otherwise; and hence the habit of taking such steps makes the consciousness of such connections familiar and vivid.

But, while mathematical discipline, and especially discipline in Geometry, is extremely useful, if not indispensable, as a means of preparing the mind to recognize throughout Nature the absoluteness of uniformities, it is, if exclusively or too habitually pursued, apt to produce perversions of general thought. Inevitably it generates a special bent of mind; and inevitably this special bent affects all the intellectual actions—causes a tendency to look in a mathematical way at questions beyond the range of Mathematics. The mathematician is ever dealing with phenomena of which the elements are relatively few and definite. His most involved problem is immeasurably less involved than are the problems of the Concrete Sciences. But he cannot help bringing with him his mathematical habits of thought; and, in dealing with questions which the Concrete Sciences present, he recognizes some few only of the factors, tacitly ascribes to these a definiteness which they have not, and proceeds after the mathematical manner to draw positive conclusions from these data, as though they were specific and adequate.

Hence the truth, so often illustrated, that mathematicians are bad reasoners on contingent matters. To previous illustrations may be added the recent one yielded by M. Michel Chasles, who proved himself incapable as a judge of evidence in the matter of the Newton-Pascal forgeries. Another was supplied by the late Prof. De Morgan, who, bringing his mental eye to bear with microscopic power on some small part of a question, ignored its main features.

By cultivation of the Abstract-Concrete Sciences, there is produced a further habit of thought, not otherwise produced, which is essential to right thinking in general, and by implication to right thinking in Sociology. Familiarity with the various orders of physical and chemical phenomena gives distinctness and strength to the consciousness of cause and effect. Experiences of things around do, indeed, yield conceptions of special forces and of force in general. The uncultured get from these experiences degrees of faith in causation such that, where they see some striking effect, they usually assume an adequate cause, and, where a cause of given amount is manifest, a proportionate effect is looked for. Especially is this so where the actions are simple mechanical actions. Still, these impressions which daily life furnishes, if unaided by those derived from physical science, leave the ordinary mind with but vague conceptions of causal relations. It needs but to remember the readiness with which people accept the alleged facts of the Spiritualists, many of which imply a direct negation of the mechanical axiom that action and reaction are equal and opposite, to see how much the ordinary thoughts of causation lack quantitativeness—lack the idea of proportion between amount of force expended and amount of change wrought. Very generally, too, the ordinary thoughts of causation are not even qualitatively valid; the most absurd notions as to what cause will produce what effect are frequently disclosed. Take, for instance, the popular belief that a goat kept in a stable will preserve the health of the horses; and note how this belief, accepted on the authority of grooms and coachmen, is repeated by their educated employers—as I lately heard it repeated by an American general, and agreed in by two retired English officials. Clearly, the readiness to admit, on such evidence, that such a cause can produce such an effect, implies a consciousness of causation which, even qualitatively considered, is of the crudest kind. And such a consciousness is, indeed, everywhere betrayed by the superstitions prevalent more or less among all classes.

Hence we must infer that the uncompared and unanalyzed observations men make, in the course of their dealings with things around, do not suffice to give them wholly-rational ideas of the process of things. It requires that physical actions shall be critically examined, the factors and results measured, and different cases contrasted, before there can be reached clear ideas of necessary causal dependence. And thus to investigate physical actions is the business of the Abstract-Concrete Sciences. Every experiment which the physicist or the chemist makes brings afresh before his consciousness the truth, given countless times in his previous experiences, that from certain antecedents of particular kinds there will inevitably follow a particular kind of consequent; and that, from certain amounts of the antecedents, the amount of the consequent will be inevitably so much. The habit of thought generated by these hourly-repeated experiences, always the same, always exact, is one which makes it impossible to think of any effect as arising without a cause, or any cause as expended without an effect; and one which makes it impossible to think of an effect out of proportion to its cause, or a cause out of proportion to its effect.

While, however, study of the Abstract-Concrete Sciences, carried on experimentally, gives clearness and strength to the consciousness of causation, taken alone it is inadequate as a discipline; and, when pursued exclusively, generates a habit of thought which betrays into erroneous conclusions when higher orders of phenomena are dealt with. The process of physical inquiry is essentially analytical; and the daily pursuit of this process generates two tendencies—the tendency to contemplate separately the factors of phenomena, which it is the aim of inquiry to disentangle, and identify, and measure, and the tendency to rest in the results of such inquiry as though they were the final results to be sought. The chemist, by saturating, neutralizing, decomposing, precipitating, and at last separating, is enabled to measure what quantity of this element had been held in combination by a given quantity of that; and, when, by some alternative course of analysis, he has verified the result, his inquiry in so far is concluded: as are kindred inquiries respecting the other affinities of the element, when they are qualitatively and quantitatively determined in like ways. His habit is to get rid of, or neglect as much as possible, the concomitant disturbing factors, and to ascertain the nature and amount of some one and then of some other; and his end is reached when accounts have been given of all the factors individually considered. So is it, too, with the physicist. Say the problem is the propagation of sound through air, and the interpretation of its velocity—say that the velocity as calculated by Newton is found less by one-sixth than observation gives, and that Laplace sets himself to explain the anomaly. He recognizes the evolution of heat by the compression which each soundwave produces in the air; finds the extra velocity consequent on this; adds this to the velocity previously calculated; finds the result answer to the observed fact; and then, having analyzed the phenomenon into its components and measured them, considers his task concluded. So throughout: the habit is that of identifying, parting, and estimating factors, and stopping after having done this completely.

This habit, carried into the interpretation of things at large, affects it somewhat as the mathematical habit affects it. It tends toward the formation of unduly-simple and unduly-definite conceptions; and it encourages the natural propensity to stop short with proximate results. The daily practice of dealing with single factors of phenomena, and with factors complicated by but few others, and with factors ideally separated from their combinations, inevitably gives to the thoughts about surrounding things an analytic rather than a synthetic character. It promotes the contemplation of simple causes apart from the entangled plexus of cooperating causes which all the higher natural phenomena show us, and begets a tendency to suppose that, when the results of such simple causes have been exactly determined, nothing remains to be sought.

Physical science, then, though indispensable as a means of developing the consciousness of causation in its simple definite forms, and thus preparing the mind for dealing with complex causation, is not sufficient of itself to make complex causation truly comprehensible. In illustration of its inadequacy, I might name a distinguished mathematician and physicist whose achievements place him in the first rank, but who, nevertheless, when entering on questions of concrete science, where the data are no longer few and exact, has repeatedly shown defective judgment. Choosing premisses which, to say the least, were gratuitous and in some cases improbable, he has proceeded by exact methods to draw definite conclusions, and has then enunciated those conclusions as though they had a certainty proportionate to the exactness of his methods.

The kind of discipline which affords the needful corrective is the discipline which the Concrete Sciences give. Study of the forms of phenomena, as in Logic and Mathematics, is needful, but by no means sufficient. Study of the factors of phenomena, as in Mechanics, Physics, Chemistry, is also essential, but not enough by itself, or enough even joined with study of the forms. Study of the products themselves, in their totalities, is no less necessary. Exclusive attention to forms and factors will not only fail to give right conceptions of products, but will even tend to make tbe conceptions of products wrong. The analytical habit of mind has to be supplemented by the synthetical habit of mind. Seen in its proper place, analysis has for its chief function to prepare the way for synthesis; and, to keep a due mental balance, there must be not only a recognition of the truth that synthesis is the end to which analysis is the means, but there must also be a practice of synthesis along with a practice of analysis.

All the Concrete Sciences familiarize the mind with certain cardinal conceptions which the Abstract and Abstract-Concrete Sciences do not yield—the conceptions of continuity, complexity, and contingency. The simplest of the Concrete Sciences, Astronomy and Geology, yield the idea of continuity with great distinctness. I do not mean continuity of existence merely; I mean continuity of causation: the unceasing production of effect—the never-ending work of every force. On the mind of the astronomer there is vividly impressed the idea that any one planet which has been by so much swerved out of its course by another planet, or by a combination of others, will through all future time follow a route different from that it would have followed but for the perturbation; and he recognizes its reaction upon the perturbing planet or planets, as similarly having effects which, while ever being complicated and ever slowly diffused, will never be lost during the immeasurable periods to come. So, too, the geologist sees in each change wrought on the earth's crust, by igneous or aqueous action, a new factor that goes on perpetually modifying all subsequent changes. An upheaved portion of sea-bottom alters the courses of ocean-currents, modifies the climates of adjacent lands, affects their rainfalls and prevailing winds, their denudations and the deposits round their coasts, their floras and faunas; and these effects severally become causes that act unceasingly in ever-multiplying ways. Always there is traceable the persistent working of each force, and the progressive complication of the results through succeeding geologic epochs.

These conceptions, not yielded at all by the Abstract and Abstract-Concrete Sciences, and yielded by the inorganic Concrete Sciences in ways which, though unquestionable, do not arrest attention, are yielded in clear and striking ways by the organic Concrete Sciences—the sciences that deal with living things. Every organism, if we choose to read the lessons it gives us, shows continuity of causation and complexity of causation. The ordinary facts of inheritance illustrate continuity of causation—very conspicuously where varieties so distinct as negro and white are united, and where traces of the negro come out generation after generation; and still better among domestic animals, where traits of remote ancestry show the persistent working of causes which date far back. Organic phenomena make us familiar with complexity of causation, both by showing the coöperation of many antecedents to each consequent, and by snowing the multiplicity of results which each influence works out. If we observe how a given weight of a given drug produces on no two persons exactly like sets of effects, and produces even on the same person different effects in different constitutional states, we see at once how involved is the combination of factors by which the changes in an organism are brought about, and how extremely contingent, therefore, is each particular change. And we need but watch what happens after an injury, say of the foot, to perceive how, if permanent, it alters the gait, alters the adjustment and bend of the body, alters the movements of the arms, alters the features into some contracted form accompanying pain or inconvenience. Indeed, through the readjustments, muscular, nervous, and visceral, which it entails, this local damage acts and reacts on function and structure throughout the whole body, producing effects which, as they diffuse, complicate incalculably.

While, in multitudinous ways, the Science of Life thrusts on the attention of the student the cardinal notions of continuity, and complexity, and contingency, of causation, it introduces him to a further conception of moment, which the inorganic Concrete Sciences do not furnish—the conception of what we may call fructifying causation. For, as it is a distinction between living and not-living bodies that the first propagate while the second do not, it is also a distinction between them that certain actions which go on in the first are cumulative, instead of being, as in the second, dissipative. Not only do organisms as wholes reproduce, and so from small beginnings are capable, by multiplication, of reaching great results; but components of them, normal and morbid, do the like. Thus a minute portion of a virus, introduced into an organism, does not work an effect proportionate to its amount, as would an inorganic agent on an inorganic mass; but, by appropriating materials from the blood of the organism, and thus immensely increasing, it works effects altogether out of proportion to its amount as originally introduced—effects which may continue with accumulating power throughout the remaining life of the organism. It is so with internally-evolved agencies as well as with externally-invading agencies. A portion of germinal matter, itself microscopic, may convey from a parent some constitutional peculiarity that is infinitesimal in relation even to its minute bulk; and from this there may arise, fifty years afterward, gout or insanity in the resulting man: after this great lapse of time, slowly-increasing actions and products show themselves in large derangements of function and structure. And this is a trait characteristic of organic phenomena. While, from the destructive changes going on throughout the tissues of living bodies, there is a continual production of effects which lose themselves by subdivision, as do the effects of inorganic forces, there arise from those constructive changes going on in them, by which living bodies are distinguished from not-living bodies, certain classes of effects which increase as they diffuse—go on augmenting in volume as well as in variety.

Thus, as a discipline, study of the Science of Life is essential; partly as familiarizing the mind with the cardinal ideas of continuity, complexity, and contingency, of causation in clearer and more various ways than do the other Concrete Sciences, and partly as familiarizing the mind with the cardinal idea of fructifying causation, which the other Concrete Sciences do not present at all. Not that, pursued exclusively, the Organic Sciences will yield these conceptions in clear forms: there requires a familiarity with the Abstract-Concrete Sciences to give the requisite grasp of simple causation. Studied by themselves the Organic Sciences tend rather to make the ideas of causation cloudy; for the reason that the entanglement of the factors and the contingency of the results is so great that definite relations of antecedents and consequents cannot be established: the two are not presented in such connections as to make the conception of causal action, qualitative and quantitative, sufficiently distinct. There requires, first, the discipline yielded by Physics and Chemistry, to make definite the ideas of forces and actions as necessarily related in their kinds and amounts; and then the study of organic phenomena may be carried on with a clear consciousness that while the processes of causation are so involved as often to be inexplicable, yet there is causation, no less necessary and no less exact than causation of simpler kinds.

And now to apply these considerations on mental discipline to our immediate topic. For the effectual study of Sociology there needs a habit of thought generated by the studies of all these sciences; since, as already said, social phenomena involve phenomena of every order.

That there are necessities of relation such as those with which the Abstract Sciences deal, cannot be denied, when it is seen that societies present facts of number and quantity. That the actions of men in society, in all their movements and productive processes, must conform to the laws of the physical forces, is also indisputable. And that every thing thought and felt and done in the course of social life is thought and felt and done in harmony with the laws of individual life, is also a truth—almost a truism, indeed; though one of which few seem conscious.

Culture of the sciences in general, then, is needful; and, above all, culture of the Science of Life. This is more especially requisite, however, because the conceptions of continuity, complexity, and contingency, of causation, as well as the conception of fructifying causation, are conceptions common to it and to the Science of Society. It affords a specially-fit discipline, for the reason that it alone among the sciences produces familiarity with these cardinal ideas—presents the data for them in forms easily grasped, and so prepares the mind for recognizing the data for them in the Social Science, where they are less easily grasped, though no less constantly presented.

The supreme importance of this last kind of culture, however, is not to be adequately shown by this brief statement. For, besides generating habits of thought appropriate to the study of the Social Science, it furnishes the mind with special conceptions which serve as keys to the Social Science. The Science of Life yields to the Science of Society certain great generalizations without which there can be no Science of Society at all. Let us go on to observe the relations of the two.